1. Technical Field
The present disclosure relates to a liquid crystal display and a thin film transistor array panel therefor.
2. Discussion of the Related Art
A liquid crystal display (LCD) is one of the most widely used flat panel displays. LCDs are used in notebook or laptop computers, desktop computer monitors and televisions. LCDs are lightweight and occupy less space than conventional cathode ray tube (CRT) displays.
The general structure of an LCD consists of a liquid crystal (LC) layer that is positioned between pair of panels including field generating electrodes and polarizers. The LC layer is subject to an electric field generated by the electrodes and variations in the field strength change the molecular orientation of the LC layer. For example, upon application of an electric field, the molecules of the LC layer change their orientation and polarize light passing through the LC layer. Appropriately positioned polarized filters block the polarized light, creating dark areas that can represent desired images.
One measure of LCD quality is viewing angle (i.e., the available area when viewing the LCD in which minimum contrast can be seen). Various techniques for enlarging the viewing angle have been suggested, including a technique utilizing a vertically aligned LC layer and providing cutouts or protrusions at pixel electrodes. However, cutouts and the protrusions reduce the aperture ratio (i.e., ratio between the actual size of a sub-pixel and the area of the sub-pixel that can transmit light). To increase aperture ratio, it has been suggested that the size of the pixel electrodes be maximized. However, maximization of the size of the pixel electrodes results in a close distance between the pixel electrodes, causing strong lateral electric fields between the pixel electrodes. The strong electric fields cause unwanted altering of the orientation of the LC molecules, yielding textures and light leakage and deteriorating display characteristics.
Another issue arises with the photo etching processes performed to form various patterns on the panels of the LCD. When a backplane for LCDs is too large to use an exposure mask, the entire exposure (e.g., irradiation of a resist) is accomplished by repeating a divisional exposure. This is called a step-and-repeat process and a single exposure area or field is called a shot. One characteristic associated with the step-and-repeat process is that the shots may be misaligned due to transition, rotation, distortion, etc., which are generated during light exposure. Accordingly, parasitic capacitances generated between wires and pixel electrodes differ depending on the shots in which they are located. These capacitance differences cause a brightness difference between the shots, which is recognized at the pixels located at a boundary between the shots. As a result, a stitch defect is generated on the screen of the LCD due to the brightness discontinuity between the shots.
Therefore, there exists a need in the art for an LCD panel and cutout configuration that allows for increased viewing angle without causing an unwanted reduction in aperture ratio and distortion of the orientation of the LC layer. There also exists a need for an LCD panel configuration that minimizes or eliminates parasitic capacitance differences between shots and corresponding brightness discontinuity.